Jack's back‹only this season he's billed as Barrymore at the Music Box Theatre on West 45th, just a few doors east of the royal-family restaurant.

Jack's back‹only this season he's billed as Barrymore at the Music Box Theatre on West 45th, just a few doors east of the royal-family restaurant. Yes, the current Barrymore‹Christopher Plummer‹has been known to frequent Barrymore's on occasion, for an atmosphere soak or whatever. And yes again, he will concede with a lusty chuckle, "it improves my performance enormously!"

The adage about dining out on anecdotes is definitely true here. Two fine actors have managed to make acting feasts for themselves out of the life and legend of John Barrymore. Plummer and, before him, Nicol Williamson are not alone in believing that the late actor's most magnificent performance was his own self, and they have done the maximum to second that motion. Both of them caught The Great Profile at the tail end of his glory trail as he weaved toward the exit in the throes (if not dementia tremors) of dapper dissipation, still mustering a boundless capacity for riotous self-mockery and ribald wit.

"I didn't see Nicol," says this year's Barrymore about last year's Jack, "but I sent my spies, and everyone seemed to say he didn't seem to take any trouble to look like him or sound like him. Good ol' Nicol‹I love his eccentricity, and I'm sure he did an interesting evening because he is an interesting and wonderful actor, and he has an interesting and crazed mind. All I can tell you is that I admire Nicol terribly as an actor. I know him. I've had terrific good drinking times with him. He knew I was going to do it because it was already in the wings, so he decided to gazump me. Well, good luck to him."

A kind of guttural last laugh goes with that tiding. God has dealt Plummer the upper hand: At 68, he still has a pretty darn great profile himself, and his matinee-idol good looks remain heartily intact. With minimum make-up and much art, he affects an uncanny facsimile of John Barrymore; by pushing that only slightly, he achieves precise throwaways of a cranky Lionel or a wispy Ethel.

Barrymore takes place in the spring of '42‹a month before John's death‹and playwright William Luce employs the fictional conceit that The Great Man is attempting one last hurrah, a Broadway production of Richard III; to that end, he enters an empty theatre to run lines with an offstage, unseen prompter (Michael Mastro). What they run is rings around a life thoroughly spent and nearing its end.

"He was creating another character, his last great role," contends Plummer. "If he couldn't do it on the stage, he'd do it in life‹so he invented this Rabelaisian creature who was a great self-mocking buffoon. I think he enjoyed it thoroughly. There must have been pain underneath, but all that rubbish about him being a tragic figure is not true. The tragedy is ours, actually, not his. The tragedy belongs to us, that he didn't continue being marvelous."

Even in his spectacular swan dive of decline, Barrymore was the beauideal for a whole generation of actors. The teen aged Plummer caught all the Barrymore movies and read Gene Fowler's loving biography, Good Night, Sweet Prince. Such knowledge and adoration of the actor pulled Plummer to the footlights himself: "I believe he helped me along. I think reading that book and seeing those early performances, relishing in the idea that he was such a gifted fellow who was also a naughty boy‹was attractive to all of us who grew up at that time."

It was about then‹when he was 16 and star struck‹that Plummer became friends with Barrymore's daughter, Diana, in Montreal. "She was doing a night-club act in which she 'modestly' billed herself as The Crown Princess of the Theatre. She did some rather bad imitations of Katie Hepburn and Tallulah and all the 'guys.' And her father. But she sang French songs absolutely enchantingly. She had a really extraordinary talent as a chanteuse, and she could have been wonderful. She could also have been a terrific actress if, again, she had had discipline enough. We kept in touch till she went through those terrible slumps and marriages. She just blew up like a balloon and was unrecognizable."

A radically different Diana‹slimmed-down and sexy‹reentered Plummer's life when he was doing J.B. for Elia Kazan on Broadway. She prevailed on him to speak to Kazan about her taking Sweet Bird of Youth on the road. "I thought, actually, 'What a good idea. She's theatrical, and it's a terrific part for her. She's off the booze. This will be a great chance for her to revitalize her career.' So I went to Gage, and Gage said, 'I don't want to touch a Barrymore.' I said, 'C'mon. All you have to do is let her read for you. She wants it so badly, and she is willing to read.' So he did. I didn't hear anything for about three weeks. Then I bumped into Gage again when he came around to see the show, and I asked him if he saw her. 'Oh, yeah, I saw her. She was so drunk we had to cancel the reading and take her out to the cab.' She'd been so scared she went back on the booze. She died only months later."

Self destruction was as much a part of the Barrymore make-up as greasepaint. "They all inherited that‹John, Ethel, Lionel, Diana, Drew. Ethel was more disciplined, but Lionel was into drugs. Morphine got him. His wife took it."

Still, this ravaged side of Broadway's true royal family only adds to their box-office allure. "I can't lie: I think everybody loves this play," confesses the current keeper of the flame. "They react wonderfully all the time, even the square audiences. Funnily enough, the play works on its own because it's about this wonderful, rich character who is trying to do something that he can no longer do. They emphasize with him about that. They love his outrageous, rebellious humor and enjoy it on that level‹particularly the young people, because the young people don't know who the hell any of the Barrymores are."

Christopher Plummer's here to tell you who. Barrymore is a real love offering.